Boring-bar



H. OTTO.

BORING BAR.

No. 341,766. Patented May 11, 1886.

A'IENT HENRY OTTO, OF BLOOMINGTON, lLLINOIS.

BORING-BAR.

SPECIFICATION forming part of Letters Patent No. 341,766, dated May 11, 1886. Application filed December 31, 1885. Serial No. 187,199. (No model.)

To all whom, it may concern.-

Beit known that I, HENRY Orro, of Bloomington, in the county of McLean and State of Illinois, have invented a certain new and useful Improvement in Boring-Bars, of which improvement the following is a specification.

My invention relates to metal boring-bars for use in drill-presses, boring-mills, or lathes; and its object is to provide effective and desirable means for adjusting and maintaining two or more tools or cutters in proper position for required diameters of bore, in surh manner that the cutters may be readily calipered to the diameter desired, and that tendency to springing of the bar may be avoided and faster feed admitted of.

To this end my invention, generally stated, consists in the combination of a radially-slotted boring-bar, two or more cutters having segmental bearing-faces fitting against corresponding seats in the slots of the bar, and adjusting-nuts engaging threads on the bar and bearing against the necks of the cutters.

The improvement claimed is hereinafter fully set forth.

In the accompanying drawings, Figure 1 is a v'iew in elevation of a boring-bar embodying my invention, the cutters being adjusted to the least diameter of bore; Fig. 2, a longitudinal central section through the same with the cutters adjusted to the greatest diameter of bore; Fig. 3, a transverse section through the same at the line co m of Fig. 2; Fig. 4, a longitudinal central section through a bar of smaller diameter, in which the cutters abut on their inner faces; Fig. 5, a view in perspective of a cutter detached, and Fig. 6 a front view of the same.

In the practice of my invention I form in the body of the boring-bar 1 a series of radial slots or recesses, 2, each of which is of proper width to receive a boringtool or cutter, 3. A segmental seat or bearing, 4, is formed at each end of each of the slots 2, against which seats, which are curved from a common center, but with different radii, correspondingly-curved bearing-faces 5 on the bodies of the cutters 3 fit when the cutters areinserted in position in the slots. Each cutter is thus maintained as against longitudinal movement in its slot, while adapted to be swung inwardlyor outwardly about the center of its bearing-faces and of the end bearings, 4, of the slot. The necks of the cutters, which are inclined outwardl y at an angle to their bodies, pass through radial recesses 6 in the bar in line with the slots 2, and are widened at their outer ends to afford additional stock at and adjacent to their cutting-edges. The outward and inward adjustments of the cutters 3 for greater or less required diameters of bore are effected by inner and outer adjusting-nuts, 7 8, each of which engages a screw-thread upon the boring-bar l. The cutters are moved outwardly by the inner nut, 7, which bears by a curved surface around its upper edge against the innor sides of the necks of the cutters, and the cutters are moved inwardly and maintained in adjusted position by the outer nut, 8, thelower portion of which incloses the bodies of the cutters 3, and bears by a curved surface upon the outer sides of their necks.

In expanding the cutters to increase the diameter of bore the outer nut, 8, is first released, and the cutters being set out to the de sired distance by the inner nut, 7, they are clamped firmly in such position by the outer nut, 8. i

In reducing the diameter of bore the inner nut is first released and moved, in reverse direction to that .for expanding, to a position proper to regulate the distance between the outer edges of the cutters, which are then clamped in position, as before, by the outer nut, 8. Either or both of the nuts may be grooved or provided with holes on its periphery, so as to be operated by a hose or pin wrench, if desired.

In boring-bars of small diameters having two cutters only, the slots which receive the same may be extended inwardly to the axis of the bar, so as to form a single diametric passage, the inner sides of the bodies of the cutters bearing in such case one against the other, as shown in Fig. 4.

The boring-bars and adj ustin g-nuts are preferably made in steel castings, the cutter-slots being formed therein by smooth cores.

I claim as my invention and desire to secure by Letters Patent-- 1. The combination of a boring-bar, a cutter having a body journaled within a radial IOO slot or recess in said bar and a neck projecting therefrom, an expanding-nut engaging a screw-thread on the bar and adapted to bear against the inner side of the neck of the'cutter, and a contracting and clamping nut engaging a screw-thread on the bar adjacent to the opposite end of the cutter, and adapted to bear against the outer side of the neck thereof, substantially as set forth.

2. The combination of a boring-bar having a series of radial slots provided with segmental seats or bearings at their ends, a series of cutters, each inserted in one of said slots, and having segmental bearing-faces fitting against the seats thereof, and adjustingnuts engaging screw-threads on the boringbar, and adapted to fit against the inner and the outer sides of the cutters, respectively, substantially as set forth.

HENRY OTTO.

Witnesses:

WILLIAM B. CARLOCK, CHARLES FREEsE. 

